Isobaric Subwoofers

[fuzz092888]

So I'm curious about isobaric subwoofers. I don't know much other than what wikipedia and a few other forum threads have told me. I know that they involve two drivers, cone facing cone, or cone to magnet. However I have a few questions and am hoping somebody out there can answer them.

1. Is a dual opposed configuration considered isobaric?

2. What benefits are there to an isobaric configuration?

3. Are there any commercially available subwoofers that use an isobaric configuration and if not why not?

I'll probably have a few more, but I think this is probably a good place to start. Thanks in advance to anyone who can help me out.

 

[j_garcia]

1) I don't think dual opposed is isobaric because part of the definition of isobaric is that the drivers are in phase

2) The main benefit would be cabinet size.

The two drivers operating in tandem exhibit exactly the same behavior as one loudspeaker in twice the cabinet. (...) The result is that the coupled driver pair (iso-group) can now produce the same frequency response in half the box volume that a single driver of the same type would require.

3) Can't think of any big names that are doing them off hand, but I am sure they are still out there. I think they were more common some years ago. **According to the Wiki, there are quite a few companies still using this method.

 

[psbfan9]

This article seems to answer most of your questions.

Audio Innovation - by Dan Marx www.danmarx.org

Advantages: Improved sonic bass response. Bass is claimed as being tighter, faster, more accurate and more pure. Vas of the driver is cut in half. The volume of enclosure required to obtain a specific frequency response can be achieved in only half the volume. This is where isobaric enclosures have their biggest advantage.

Disadvantages: Wasted amplifier power to driver the internal sub. Efficiency of the system is down 3 dB as compared to a single driver due to the added cone mass and the reduced Vas. When you compare isobarics to a system which houses two drivers each in their own enclosure, this system wis actually 6 dB less efficient.
Best Applications Where size is a big issue. When you want the box to be very small. Where more accurate bass is more important than lots of bass. If you have a hefty amplifier with plenty of juice to spare and a driver that can handle a good amount of power. Suited for music, home theater and car. Not used too often these days.

 

[fuzz092888]

Thanks guys, I was specifically thinking of the cinepro evo2 subwoofer since I see that they are isobaric and I was curious what that exactly meant and what $7000+ got you in a subwoofer. Obviously that's way out of my price range, but I was wondering what kind of performance you could get from those things compared to the multitude of other options at half the price. I guess that's why Cinepro wants you to buy them in pairs.

 

[theJman]

The only company I know that makes a traditional isobaric subwoofer is Pinnacle with their SuperSonic. Kreisel Sound has the DXD-808 and DXD-12012, which I suppose is a variation of that design. James Loudspeakers has another take on it, which they call Energy Multiplied Bandpass. It has an active driver and a PR in an isobaric configuration. Their one powered model is the EMB1000, but they also have half a dozen passive models (which, sadly, bear a striking resemblance to shipping crates).

 

[fuzz092888]

The only company I know that makes a traditional isobaric subwoofer is Pinnacle with their SuperSonic. Kreisel Sound has the DXD-808 and DXD-12012, which I suppose is a variation of that design. James Loudspeakers has another take on it, which they call Energy Multiplied Bandpass. It has an active driver and a PR in an isobaric configuration. Their one powered model is the EMB1000, but they also have half a dozen passive models (which, sadly, bear a striking resemblance to shipping crates).

Very interesting designs, although I'm not sure I'd want to spend $48000 on the quatro quatro kreisal's

Man, shipping crate is right.